Safety trigger for pneumatic tools



Sept. 5, 1944. A. J. DE PAEPE SAFETY TRIGGER FOR PNEUMATIC TOOLS Filed March 31, 1943 A INVENTOR .J.DePaepe mmm A? TTYS Patented Sept. 5, 1944 UNITED STATES PATENT OFFICE p SAFETY TRIGGER FOR PNEUMATIC TooLs Arthur J. De Paepe, Stockton, Calif.A l Application March 31, 194s, serial No. 481,189 l 9 claims. (C1. 'i4- 503) This invention relates generally to an improvement in uid pressure actuated tools such as pneumatically operated hand drills o-r the like, and in particular the invention is directed to, and it is an object toprovide, a safety trigger for tools of the identified type.

Certain commonly used iiuid pressure actuated tools are presently controlled by a trigger which is elongated and projects some distance from the tool handle. By reason of this projection,

accidental starting of the tool is likely to occur vide'a safety trigger for fluid pressure actuated' tools, which incorporates Yas one of its advantageous features a finger or thumb pad` which lies very close to the tool handle and without any substantial projection; the trigger being operable only upon sliding movement of said pad,

, as by the operators thumb, lengthwise of the tool whereby to release a safety catch and to then open the fluid lcontrol valve.

An additional object of the invention is to provide va safety trigger for fluid pressure. actuated tools, which trigger includes anelongated plate-like member disposedron edge and engaging in a substantially matching slot in the upper end portion of the tool handle, a nger pad on n said plate exteriorly of the handle, said trigger plate being mounted in said slot for limited lineal movement, and a nub projecting inwardly from the inner edge of said trigger plate; there being a depressible valve control stem disposed in the path of said nub whereby upon predetermined movement of the trigger plate in said direction, to engage and depress said stem so as to open the valve and cause operationof p the tool.

A still further object of this invention is to provide a safety trigger, as in the preceding paragraph, in` which said stem is depressed by the nub upon lineal movement of the trigger plate from an advanced position; there being a catch shoulder formed in the lower edge of said plate and engaging in holding relation with a portion of the tool handle when the trigger plate is in `said advanced or off position whereby to prevent accidental movement or retraction of the trigger plate to an on position.`

A further object of theV invention is to produce a simple and inexpensive device and yet one which will be exceedingly eiective for the purpose for which it is designed.

These objects IV accomplish by means of such structure and relative arrangement of parts as will fully appear by a perusal .of the following specification and claims. l

In the drawing similar characters of reference indicate corresponding parts vin `the several views:

Figure 1 is a side elevation, partly in section, of a uid pressure actuated hand drill embodying the invention, and showing the safety trigger in a relatively advanced or off position.

Figure 2y is a similar but fragmentary viewk illustrating the safety trigger in retracted or on position. f

Figure 3 is an upper edge view of the safety trigger, detached from the tool.

Referring now more particularly to the Icharacters of reference onr the drawing, the numeral `I indicates generally a fluid pressure actuated tool, here shown as a hand drill, which includes a housing 2 in which is enclosed a'iiuid actuated motor, a tool holder or chuck 3 driven from the motor within housing 2, and a pistol-grip type handle 4 which is connected with the remainder of the tool by a gooseneck 5 included in integral relation with said handle. 'The above is a conventional tool and my invention resides in the provision of a uniquesafety trigger therefor, and which comprises the following:n

The pistol grip handle 4 at its top or crown 6, which is rounded, is formed with an outwardly opening slot 'l whichis cut in a Iplane lengthwise of the tool, and which slot is of substantial depth, and the bottom of which is disposed at a rearward and downward incline when the tool is horizontal. Y

A trigger plate 8 engages in slo-t l with a relatively close running t, the outer 'edge of said plate substantially conforming to the exterior configuration of the adjacent rounded portionV of the top 6 of the handle; the lower and upper end portions 9 and l 0 respectively of the trigger plate normally projecting a slight distance beyond corresponding ends of the slot 1. A thumb pad Il is mounted'transversely on the upper edge of the trigger plate 8 adjacent its upper end portion I 0 and inclosely overlying relation to the handle. 1t will be seen that by virtue'of theabove arrangement there is no great outward projection of any part of the trigger plate or thumb pad relative to the handle.

The trigger plate 8 is formed with a longitudinally extending slot I2 which is elongated in generally parallel relation to the inner edge of said plate and the bottom line of the handle slot 1. This plate slot 8 is disposed closer to end portion 9 of the plate than to end portion I0, and a cross pin I3 extends between the sides of handle slot 'I and passes through the plate slot I2.

A nub I4 is formed on and projects inwardly from the inner edge of the trigger plate intermediate its ends and slightly ahead of theupper end of slot I2. When the trigger plate is advanced to off position, i. e. moved upwardly and forwardly until pin I3 seats in the lower end of slot I2, the nub I4 is disposed in engagement with but slightly ahead of the upper end of a depressible stem I5 which projects into the slot I from below, and which is part of the standard valve arrangement of the tool. This depressible stem is connected with' a plunger I6 which in turn functions to actuate a valve I'I mounted to cooperate with a' valve seat I8 in a fluid passage I9 formed in the handle and through which passage fluidv under pressure is supplied to the tool motor. The valve I1 is spring-pressed from beneath by means of a compression'spring 20 which normally urges said valve to closed position and raises the depressible stem I5. -The handle at its lower end is formed with a fitting 2I for connection with a flexible conduit (not shown) which supplies the duid pressure to the tool. It will be seen that upon depression of the stem I5 and consequent opening of the valve Il, fluid under pressure flows through the passage I9 in the handle to the tool motor to operate the latter. Depression of stem I5 is accomplished by the safety trigger las follows:

The inner edge of vtrigger plate 8 at its ends 9 and I'U rides the corresponding portion of the bottom of slot l, which serves to guide lineal movement of said plate between on and ofi positions; the inner edge of said pla'te at its upper 'end I0 being formed with a downwardly facing 'shoulder 22 which engages over the adjacent top portion ofthe handle when the trigger plate is in off position, as shown in Fig. l.' When in this position the trigger plate can be moved to on position, as shown in Fig. 2, only upon release of said shoulder 22 followed by rearwardly inclined sliding movement o'f the` trigger plate under the influence of A'the operators thumb on thumb pad II. The cross pin I'3engages in the elongated plate slot I2 with slight loose play so as to permit the plate to be rocked slightly and the shoulder 22 to be released from holding position.

Upon movement of the trigger plate from off to on position, the nub rides forcefully onto the upper end of stern I5, depressing the latter and opening the valve II; the trigger plate being held against free rotation about pin I3' as the inner edge of said plate engages adjacent its ends with corresponding end 'portions of the bottom of the 'slot 1.

'By reason of the above described safety trigger structure, the tool can be easily turned on and ofi by the operator, and yet when said safety trigger is in the off position, as shown in Fig. 1, there is little likelihood of said trigger being accidentally dislodgedand shifted to on position when the tool is laid aside by the operator, or is otherwise in an inoperative position. This is because no exterior pressure, when exerted against the trigger in any other than the one definite direction as described, can effect movement of the trigger from its locked position.

From the foregoing description it will be readily seen that I have produced such a device as substantially fulfills the objects of the invention as set forth herein.

While this specication sets forth in detail the present and preferred construction of the device, still in practice such deviations from such detail may be resorted to as do not form a departure from the spirit of the invention, as defined by the l appended claims.

Having thus described my invention what I claim as new and useful and desire to secure by Letters Patent is:

1. A safety trigger for a duid pressure actuated tool which includes a hand grip having an outwardlyv opening longitudinal slot therein, and a valve control stem projecting into the slot from the bottom of the latter, said trigger comprising a trigger plate, means mounting said plate in the slot for liinited lineal sliding movement clear of said stem, an element projecting inwardly from the plate operative to engage and depress said stem upon sliding of the plate to a predetermined position and a finger pad mounted on -the plate exteriorly of the hand grip.

2. A safety trigger for a fluid pressure actuated tool which includes a hand grip having an outwardly opening longitudinal slot therein, and a valve control stem projecting into 'the 'slot from the bottom of the latter, said trigger comprising a trigger plate, means mounting said plate in the slot for limited lineal sliding Vmovement clear of said stem, an element projecting inwardly from the plate operative to engage and depress said stem upon sliding of the plate to va predetermined position, the outer edge of the plate being adjacent and generally symmetricalV-to the exterior vportion of the hand grip along said slot, and a nger pad xed on said outer edge of the plate and closely overlying said exterior Aportion of the hand grip. I

3. Asafety rtrigger as in claim 2- in which said plate includes a catc-hshoulderon the inner' edge of theplate in position lto engage over one end of vthe bottom of the slot when the plate is disposed with said elementin lnon-"depressing relation to the stem whereby to -releasably 'hold the plate against movement to stemdepre'ssing position; the plate being mounted for limited rocking movement to permit release offy said shoulder preparatory to movement of said plate AtoV said stem depressing position.

4. 'A safety trigger ior a fluid pressure actuated tool which includes a hand grip having an outwardly opening longitudinal slot therein, and a valve control stem projecting into the slot rfrom the bottom of the latter, said trigger comprising a trigger plate, means vmounting said plateV in the'slotvfor limited vlineal sliding movement clear of said stem, an element projecting inwardly from the plate operative to engage and-depress said stem upon sliding of the plate to a prede'- termined position and a finger pad mountedV` on the plate ex-teriorly of the hand grip; said plate mounting Vmeans comprising av cross pin 'xed in said slot, the plate having an elongated slot therethroughlengthwiseof its ldirection' of move'- ment, thecross pin extending through said slot.

y5. A safety trigger for a fluid pressure actuated tool which includes a hand grip having an outwardly-opening longitudinal slot therein, and a valve controlA stem projecting into-the slot from the bottom of the latter, said trigger comprising a trigger plate, means mounting said plate in the slot for limited lineal sliding movement clear of said stem, an element projecting inwardly from the plate operative to engage and depress said stem upon sliding of the plate to a predetermined position and a nger pad mounted on the plate exteriorly of the hand grip; said plate mounting means comprising a crossY pin fixed in said slot, the plate having an elongated slot therethrough lengthwise of its direction of movement, the cross pin extending through said slot, and the inner edge of the plate adjacent its ends riding the bottom of the slot.

6. A safety trigger as in claim in which said plate includes a catch shoulder formed on its inner edge in position to engage over one end of the bottom of the hand-grip slot when the plate is disposed with said element in non-depressing relation to the stem whereby to releasably hold said plate against movement to a stem depressing position; the plate having slight loose play relative to the cross pin to permit of limited rocking movement of the plate to release said shoulder preparatory to movement of said plate to stem depressing position.

7. A safety trigger for a iiuid pressure actuated tool which includes a hand grip having an outwardly opening longitudinal slot therein, and a valve control stem projecting into the slot from the bottom of the latter, said trigger comprising a trigger plate disposed edgewise in said slot for relative sliding movement therein, said plate having an elongated slot therethrough extending in the direction of sliding movement, a cross pin' fixed in the hand grip slot and passing through the elongated plate seat, the inner edge of the plate engaging at its ends with corresponding end portions of the bottom of the hand grip slot. said inner edge of the plate and adjacent slot bottom being formed so that the plate is slidable in a path clear ofA said stem, a nub projecting inwardly from said inner edge of the plate positioned to engage and depress said stem upon rearward sliding movement of the plate, and a linger pad mounted on the plate exteriorly of the hand grip and closely overlying the latter.

8. A safety triggerv forv a iluid pressure actuated tool which includes a hand grip having an outwardly opening longitudinal slot therein, and a valve control stem projecting into the slot from the bottom of the latter, said trigger comprising a trigger plate disposed edgewise in said slot for relative sliding movement therein, said plate having an elongated slot therethrough extending in the direction of sliding movement, a cross pin xed in the hand grip slot and passing through the elongated plate seat, the inner edge of the plate engaging at its ends with corresponding end portions of the bottom of the hand grip slot, said inner edge of the plate and adjacent slot bottom being formed so that the plate is slidable in Aa path clear of said stem, a nub projecting inwardly from said inner edge of the plate positioned to engage and depress said stem upon rearward sliding movement of the plate, and a finger pad mounted on the plate exteriorly of the hand grip and closely overlying the latter; the inner edge of the trigger plate having a catch shoulder thereon adjacent its forward end adapted to engage over the corresponding end of the bottom of thehand grip slot, and said plate being capable of limited rocking movement relative to the hand grip and about said cross pin whereby'to permit of release of said shoulder preparatory to rearward sliding movement of the plate and engagement of the nub with said stem to depress the latter. Y

9. A safety trigger as in claim 2 in which said slot is disposed at a downward and rearward incline when the tool is horizontal; and in which said plate is mounted for sliding movement parallel to said incline.

ARTHUR J. DE PAEPE. 

